Interfacial Ru–O–W Orbital Coupling Enables Lattice Oxygen Stabilization for Enhanced Acidic OER

Abstract Ruthenium dioxide (RuO 2 ) is highly active for acidic oxygen evolution reaction (OER) but suffers from instability due to lattice oxygen oxidation. Herein, we construct a RuO 2 /WO 3 heterostructure that leverages strong Ru–O–W interfacial bridge bonding to fundamentally modulate electronic structure and reaction pathways. Density functional theory calculations reveal pronounced orbital hybridization at the interface, resulting in a simultaneous downshift of the Ru d‐band and O p‐band centers. This modulation weakens the Ru–O* interaction while strengthening the Ru–O bonds, effectively suppressing the lattice oxygen mechanism. Benefiting from this electronic structure regulation strategy, the RuO 2 /WO 3 electrode delivers a substantially low overpotential of 203 mV at 10 mA cm −2 and maintains exceptional structural and electrochemical integrity over 200 h of continuous acidic OER operation. This work unveils a new paradigm of orbital‐level interface engineering for stabilizing noble‐metal catalysts under harsh acidic conditions.